Printing plate cylinder saddle

ABSTRACT

A printing plate cylinder saddle is provided with construction features for mounting on a printing plate cylinder and for attaching a thin, flexible printing plate. Identical plate engaging assemblies are provided at each end of the saddle and are selectively operable to releasably clamp and interlock the lead edge of the flexible plate in register along the lead edge of the saddle or to interlock and exert a constant tension upon the tail edge of the flexible plate along the trailing edge of the saddle.

United States Patent Etchell et al. 1 Aug. 7, 1973 [54] PRINTING PLATECYLINDER SADDLE 3,603,255 9/1971 Homer 101/378 3,626,848 121971 T fl t l101 415.1 [751 fiche", Owners 3,646 886 3l1972 11:02:11; et al. 10 l/378Bohdan Washchynsky, Westchester, both f "L FOREIGN PATENTS ORAPPLICATIONS [73] Assigneez North American Rockwell 1,115,936 6/1968Great Brltaln 101/4151 Corporamm Pittsburgh Primary ExaminerRobert E.Pulfrey [22] Filed: June 12, 1972 Assistant ExaminerPaul T. Sewell [211App. No: 261,876 stigma-John R. Bronaugh, Damel H. Dumbar [57] ABSTRACT2% A printing plate cylinder saddle is provided with con- 415 1struction features for mounting on a printing plate cyl- 1 0 can inderand for attaching a thin, flexible printing plate. Identical plateengaging assemblies are provided at [56] Reerences cued each end of thesaddle and are selectively operable to UNITED STATES PATENTS releasablyclamp and interlock the lead edge of the 3,110,255 11/1963 Jeschke etal. l01/415.1 flexible plate in register along the lead edge of the sad-3,702,098 11/1972 Eburn lOl/4l5.l dle or to interlock and exert aconstant tension upon 3,470,817 10/1969 Helmllcher et a1. 101/378 thetail edge f the flexible plate along the trailing edge 3,533,355 10/1970Wall 101 4151 Ofthe Saddle 3,537,395 11 1970 Prince et al.. 101/3783,587,464 6/1971 Wessels 101/4151 5 Claims, 6 Drawing Figures PATENIED 73. 750.572

sum 3 or 3 PRINTING PLATE CYLINDER SADDLE SUMMARY A printing platecylinder saddle is provided with means for mounting on a rotary printingpress printing plate cylinder and with identical lockup assemblies atboth ends of the saddle which are selectively positionable forinterchangeably engaging either the lead or the tail edge of a flexibleprinting plate of the type having lead edge and tail edge flanges formedessentially at right angles to the plate principal surface. Each lockupassembly includes a series of plate engaging fingers and associatedinterlocking tabs which are movable by means of a convenient manuallyoperable lever between two plate engaging positions. In one position thefingers and interlocking tabs radially restrain and securely clamp thelead edge flange of the printing plate in register position along thelead edge of the saddle. In the other position, the fingers and tabs areadapted to radially restrain and exert constant tension on the tail edgeflange of the printing plate. Thus, the lead edge of a plate mayconveniently be mounted in register at either end of the saddle and bysimply moving two convenient levers it is securely locked in positionand placed under a constant tension.

DRAWINGS FIG. I is a schematic end view of a typical rotary printingpress printing plate cylinder having two semicylindrical saddles inaccordance with the present invention mounted thereon;

FIG. 2 is a developed view taken along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view along line 3-3 of FIG. 2;

FIG. 4 is an exploded view of the flexible printing platerestraining/tensioning assembly provided at each end of the disclosednovel saddle;

FIG. 5 is a perspective view ofa spring element of the FIG. 4 assembly;and

FIG. 6 is a fragmentary perspective view illustrating the flanged edgeof a flexible printing plate for which the saddle lockup assembly ofFIG. 4 is useful.

The invention subsequently described herein is disclosed schematicallyin FIG. I as applied to the printing plate cylinder 10 of a rotarynewspaper printing press. The number of printing plates and thus thenumber of pages to be printed by such cylinder will vary depending uponthe size and type of printing press involved but generally suchcylinders are adapted to accommodate two plates around and four platesacross so that eight pages are printed during each cylinder revolution.Such cylinders may be driven in either a clockwise or counterclockwisedirection, as viewed in FIG. 1, depending upon the configuration andwebbing of the press, but for the purpose of illustrating this inventionit will be assumed that the cylinder will rotate in a clockwisedirection as indicated by the arrow.

When printing with thin, flexible printing plates, as distinguished fromthe more conventional stereotype printing plates, such flexible platesmust be mounted on saddles of the required thickness and radius ofcurvature so that the peripheral or printing surfaces of the plates willbe adequately supported and maintained at the proper radius. Two suchsaddles are indicated as 11 and 12 in FIG. 1 and it will be understoodthat they are secured to the surface of printing plate cylinder 10 byconventional stereotype printing plate tension lockup means as is wellknown in the art.

The means whereby the flexible printing plates are secured in positionon the saddles is illustrated in FIGS. 2 and 3 wherein the lockupassembly indicated by the numeral 20 is shown as being mounted at thelead edge of the saddle 11 for engaging the lead edge ofa flexibleprinting plate whereas the identical lockup assembly indicated by thenumeral 21 is shown as being mounted on the trailing edge of saddle 12.It will be understood, of course, that identical lockup assemblies aredesirably provided at the other trailing and leading edges of therespective saddles also.

All of the assemblies are identical in structure and function andtherefore, the following detailed description will be directed to thelockup assembly 20 at the lead edge of the saddle l1 and the samereference numberals will be used to identify corresponding elements inthe assembly 21.

As shown in FIGS. 2 and 3 the saddle 11 comprises a semi-cylindrical,generally plate-like body member, preferably formed of lightweight metalsuch as magnesium or cast aluminum, for example, the inner surface ofwhich is milled away or relieved along the lead edge thereof toaccommodate the lockup assembly 20. As may be seen best in FIG. 3,portions 22 of the body member adjacent the lead edge relief areretained and these are provided with undercut scarf notches 23 which areadapted to receive the cooperating cylinder tension lockup hooks forstereotype plates (not shown) by means of which the saddle 11 is lockedonto printing plate cylinder 10.

The plate clamping assembly 20 adapted to be mounted in the relievedportion of the saddle body is shown best in FIG. 4, and is comprised ofa substantially L-shaped base member 27 which extends acrosssubstantially the full width of the saddle, a cover plate 28 which issimilar in shape and size to the base mems ber, a slide bar 29, and asupport bracket 31. The bar 29 and bracket 31 are sandwiched between thebase member and cover plate and are mounted for movement relativethereto for plate clamping purposes.

The slide bar 29 is fabricated from a flat, rectangular metal plate andis provided with a series of three aligned, axially disposed, elongatedslots 32 centrally thereof. Adjacent each end and on the side thereoffacing the support bracked 31 the slide bar also is provided withrollers 33 which are rotatably mounted on rivets or the like secured tothe bar. At one end of bar 29a V-shaped groove 34 is provided to receivethe arm 36 of a bell crank lever 37 that ispivotally mounted between thebase member 27 and cover plate 28 and it has a second arm 38 whichprojects sufficiently beyond the edge of the saddle to constitute amanual control lever whereby the slide bar can be shifted laterally forpurposes to be explained hereinafter.

The support bracket 31 also is fabricated from a flat, rectangular metalplate and it is somewhat longer and wider than the slide bar.Rectangular openings 39 are formed in the body portion thereof toprovide clearance for the scarfed projections 22 of the saddle and atthe base thereof the bracket is provided with three elongated slots 41which are aligned with but extend in a direction normal to the slots 32in the slide bar 29. The base portion of the bracket also is providedwith a diagonally disposed slot 42 adjacent each end thereof and theseslots are aligned with and are adapted to receive the rollers 33 of theslide bar in the assembled position. Reverse angled pockets 43 areformed at the ends of the slots 42 and as will become clear hereinafterthese pockets serve to maintain the bracket in each of its plateclamping positions.

The elements thus far described are assembled as a unitary structure bymeans of rivets 44 and 45 which extend through apertures providedtherefor in the base member 27 and cover plate 28. The rivets 44 alsoextend through the outermost of slots 32 and 41 in the slide bar 29 andbracket 31, respectively, and they are provided with spacers 46 whichfit snugly without binding in the respective slots 32 and 41 and serveto maintain clearance between the base member and cover plate so thatthe slide bar 29 and support bracket 31 are caused, when actuated, tomove at right angles relatively to each other. The rivet 45 also passesthrough an opening 47 provided in the bell crank 37 and constitutes thepivot axis for said lever.

After assembly of the unit as just described, it is removably mounted tothe saddle by means of the bolts 48 which pass through openings in thebase member and cover plate as well as spacers 49 and the ends thereofare received in tapped holes provided therefor in the saddle. The centerbolt 48 also passes through the base member and cover plate and itcarries a spacer 49 which is adapted to fit snugly in the center slots32-4l of the slide bar and bracket, respectively.

From the description thus far, it will be evident that when the bellcrank 37 is pivoted in a clockwise or counterclockwise directioncorresponding lateral movement will be imparted to the slide bar 29which motion is permitted by the elongated slots 32 whereas said slotscoact with the spacers 46 and 49 to prevent the slide bar from moving ina circumferential direction. Due to the coaction of the rollers 33 ofthe slide bar in the diagonal slots 42 of the support bracket 31, thelatter will be moved back and forth in a circumferential directionbetween its two plate clamping positions, the elongated slots 41permitting such circumferential movement while coacting with the spacers46 and 49 to preclude lateral movement of the bracket.

For the purpose of radially restraining, clamping, and tensioning aflexible printing plate on the saddle, one edge of the support bracket31 is projected beyond the base member 27 and cover plate 28 and isprovided with a series of plate tentioning fingers 51 and interlockingfingers 52 extending across the full width thereof. Such fingers arepreferably fabricated from a strip of spring steel which is bent into agenerally Z- shaped configuration haveing a base portion 53, a verticalwall 54, and a finger portion 56. The finger portion 56 and wall 54 areslotted as at 57 thereby forming two tension fingers 51 which areseparated by an intervening finger 52, the latter being bent at an anglerelative to the wall portion 54 such that it projects somewhat ahead ofthe tension fingers 51 as indicated more clearly in FIG. 3. In thoseportions of the vertical wall 54 forming part of the tension fingers 51,interlocking tabs 58 are punched from the spring steel so that theyproject rearwardly with respect to the fingers 51 and they are bent atan obtuse angle or sloped with respect to the vertical wall as is moreclearly indicated in FIG. 3.

All of the respective fingers and tabs across the full width of thesupport bracket obviously may be formed from one continuous piece ofspring steel but it is preferred to form them as independent elementseach of which consists of two tension fingers and an intervening lockingfinger. In such case, four such elements normally are required for astandard size saddle and they are mounted in aligned relation along theprojecting edge of the support bracket 31 as illustrated in FIG. 4. Inthe preferred construction, the base portion 53 of each finger elementis sandwiched between the bracket 31 and one leg 55 ofa bar 59 ofL-shaped cross-section and both the finger element and the bar aresecured in position on the bracket by means such as the rivets 60. Thebar 59 is mounted over the finger element in a manner that the other leg55a thereof extends parallel with and closely adjacent to the verticalwall 54 of the finger element and it serves to protect the tensionfingers 51 against damage as well as to reinforce the fingers as theymove to the plate clamping position as will be explained hereinafter. Itwill be noted that the leg 55a of the L-shaped bar is cut away in thearea adjacent the interlocking finger 52 so that said finger can projectforwardly of the tension fingers 51 and thereby perform its intendedfunction.

For use in conjunction with the present saddle lockup means, theprinting plates are pre-bent and punched in a manner as indicated inFIG. 6. As shown, the edges (leading and trailing) of the plate 61 arebent inwardly at substantially a angle relative to the body thereof toform a flange 62 which in turn is provided with two series of slots 63and 64 respectively. The slots 63 are located so that they will coincidewith a groove 66 formed in the end face of the saddle 11 and they areadapted to have coaction with the locking tabs 58 to radially restrainthe lead edge of the plate in register position on the saddle. The slots64 on the other hand are located substantially at the junction betweenthe flange 62 and body 61 of the plate and they are adapted to havecoaction with the interlocking fingers 52 to radially restrain thetrailing edge of the plate in position.

Although the function of the lockup assemblies should be clear from theforegoing description, a brief explanation of the procedure involved inmounting a plate on the saddle is considered helpful. Assuming that thecylinder 10 (FIG. 1) will be rotating in a clockwise direction, thelockup assembly 20 on the saddle 11 will be in the lead edge position.Referring to FIG. 3, the lever 38 must first be moved in a clockwisedirection (as viewed in FIG. 2) thereby shifting the slide bar 29 andtherewith the rollers 33 to the right. As the rollers 33 traverse thediagonal slots 42, the bracket 31 will be moved in acircumferentialdirection from its retracted (FIGS. 2 and 3) positionwherein the vertical wall 54 of the tension fingers 51 is adjacent theend face of the saddle, to its projected position (see assembly 21,FIGS. 2, 3) wherein said wall 54 is spaced from the end face of thesaddle. This will provide clearance for the flange 62 at the lead edgeof the plate to be inserted between the face of the saddle and the clampassembly with the slots 63 therein coincident with the groove 66. Itshould be noted, although not shown in the drawings, that locating pinsor studs may be mounted in the end faces of the saddle and cooperatingholes provided in the flanged leading and trailing edges of plate 61 toobtain proper lateral registration of the plate on the press platecylinder prior to clamping and tensioning.

Once the lead edge of the plate is in position, the lever 38 is moved incounterclockwise direction whereupon the rollers 33 and slots 42 willcoact to retract the bracket 31 as the slide bar 29 moves to the left asviewed in FIG. 2. Movement of the bracket 31 continues until it assumesthe clamping position as illustrated in FIG. 3 wherein the tabs 58 areinterlocked in the slots 63 of the plate and project into the groove 66of the saddle. In this position the lead edge of the plate is positivelyradially restrained by the tabs 58 against centrifugal forces actingthereon at high speeds.

The angle of the tabs 58 also serves a secondary but important function.As the bracket 31 is retracted toward its plate clamping position, theleading edge of the tabs 58 will initially engage the upper edges of theslots 63 of the plate 61. As movement of the bracket continues, theangle of the tabs 58 will cause the flange 62 of the plate to be drawnradially inwardly of the saddle until the body portion of the plate isbrought into and thereafter maintained in intimate contact with theouter surface of the saddle. This is important because the plate has anatural tendency to spring away from the saddle and if any clearanceremains between the plate and the saddle after the plate is locked up inposition, it will permit a flexing action which can have an adverseeffect upon the printed impression as well as cause premature crackingof the plate during operation.

During the retraction of the bracket 31 the radially disposed wall 55aof the L-shaped bar 59 engages and thus serves to reinforce therelatively flexible fingers 51 so that the tabs 58 will penetrate theslots 63 to the maximum extent and thus positively draw down the plateinto intimate contact with the saddle.

After the lead edge of the plate has been radially restrained andclamped into position, the tail edge is secured by the assembly 21 atthe trailing edge of the saddle. In this instance, the lever 38 of theassembly 21 would first be moved in counterclockwise direction as viewedin FIG. 2, thereby shifting the slide bar 29 laterally so that therollers 33 will traverse the diagonal slots 42 and thus retract thebracket 31 and fingers 51 to a position adjacent the end face of thesaddle. The tail end flange 62 of the plate 61 is then positioned overthe fingers 51 and 52 whereupon the lever 38 is moved in clockwisedirection to project the fingers 51 and 52 to the position illustratedin FIG. 3

During their movement to the illustrated projected position the slopedportions of interlocking fingers 52 project through the slots 64 in theplate 61 thereby securing the plate against any centrifugal forcesacting thereon during operation of the press and here again because ofthe angle of said fingers the tail edge of the plate is drawn radiallyinwardly and maintained in intimate contact with the peripheral surfacesof the tension fingers 51. The latter fingers in turn, are adapted toengage the flange 62 of the plate prior to reaching their fullyprojected position so that they are bent backward to a predeterminedextent upon final movement of the bracket 31 to its fully projectedposition. As a result, the fingers 51 become preloaded and thus exert aconstant, circumferentially directed tension upon the plate to maintainit in intimate contact with the saddle during operation of the press.

With the flexible printing plate clamped in operative position as justdescribed, it is obvious that reactive forces acting upon the respectiveclamping and ten- 6 sembly 20, a reactive force will be exerted againstthe fingers 51 tending to move the bracket 31 away from the end face ofthe saddle 11, to the left as viewed in FIG. 2. This force coupled withnormal vibration under operating conditions would result in the slidebar 29 shifting laterally, due to the effect of the diagonal slots 42 onthe rollers 33, thereby relaxing the securing effect of the fingers 51and tabs 58 on the plate. The same condition would exist with theassembly 21 except that the reactive force would be exerted in theopposite direction.

To preclude such unintended motions, the previously mentioned reverseangled pockets 43 are provided at each end of the diagonal slots 42which perform a toggling function in combination with the rollers 33 andthus serve to releasably retain the bracket 31 in either one of itsplate clamping positions. With reference to FIG. 2 it will be evidentthat as the slide bar 29 is moved to the left, the rollers 33 willtraverse the slots 42 thereby retracting the bracket 31 to its lead edgeplate clamping position and during the final movement of the slide bar,the rollers 33 will pass over the apex of the slots 42 and drop into thepockets 43. As a result, the reactive force acting on the bracket 31 andtending to move it in a circumferential direction away from its plateclamping position will merely force the rollers into the pocket 43 andthus lock the slide bar 29 against any unintended lateral movement. Thesame function is achieved when the assembly is moved to the platetensioning position as representd by the assembly 21 in FIG. 2, in whichcase the rollers 33 drop into the pockets 43 at the opposite end of theslots 42 to thereby toggle the assembly in the tail edge platetensioning position. This arrangement is completely effective to retainthe respective assemblies against unintended movement and yet the toggleeffect presents minimum resistance against manual movement of the lever38 so that the need for an auxiliary tool or the like to manipulate saidlever for plate clamping purposes is completely obviated.

What is claimed is:

1. A saddle for attaching to a printing cylinder a flexible printingplate having like flanged and slotted leading and trailing edges formedessentially at right angles to the plate principal surface andcomprising, in combination: 7

a rigid plate-like body of generally semi-circular cross-sectionalconfiguration defined in part by a pair of longitudinal edges;

attachment means adjacent the concave surface of said plate-like bodyfor mounting said body on a printing press cylinder;

a pair of plate retention members respectively located adjacent saidbody pair of longitudinal edges and each having alternate extremepositions for clamping and for tensioning;

mounting means securing said plate retention members to said body andrestricting'movement of said plate retention members to circumferentialdirections relative to said body longitudinal edges and relative to saidretention member clamping and tensioning positions;

a pair of actuator means respectively connected to said pair of plateretention members and each being mounted for acutatio n to alternatelymove a cooperating connected plate retention member to said alternateextreme plate clamping and plate tensioning positions; I

first means in each said plate retention member for engaging andradially restraining a printing plate flanged and slotted leading edgeand for urging said engaged plate flanged and slotted leading edgeagainst one of said body longitudinal edges on movement of said plateretention member by the connected one of said actuator means to one ofsaid extreme plate clamping positions; and

second means in each said plate retention member for engaging andradailly restraining a printing plate flanged and slotted trailing edgeand for urging said engaged plate flanged and slotted trailing edge awayfrom the other of said body longitudinal edges on movement of said plateretention member by the connected one of said actuator means to one ofsaid extreme plate tensioning positions.

2. The saddle defined by claim I wherein each said actuator meanscomprises an actuator bar element having slots and movable inlongitudinal directions with respect to said plate-like body, andwherein said plate retention member connected to said actuator means barelement is provided with diagonal slot elements and with cooperatingroller cams each further cooperating with said actuator bar elementslots, said roller cam and diagonal slot elements directing forcesdeveloped by said connected actuator means from lines along said barelement longitudinal directions to lines along said plate retentionmeans circumferential directions to move the connected one of saidretention members to said clamping position and to said tensioning;position when said actuator means is operated to move said mountingmeans to and from said plate tensioning position.

3. The invention defined by claim 2 wherein said diagonal slot elementsare provided at each slot end with a reverse-angle pocket acting as adetent for the cooperating one of said roller cam elements, saidreverseangle pockets locating the cooperating actuator means andmounting means in said plate clamping and plate tensioning positions.

4. The invention defined by claim 1 wherein said plate retention memberseach have spring-like finger members oriented relative to saidplate-like body in a generally radial direction and extendingsubstantially throughout the longitudinal extent of said plate-likebody, said finger members further comprising first finger membersengaging the flexible printing plate flanged trailing edge whentensioning said flexible printing plate and having sloped surfaceportions engaging slots in said flexible printing plate flanged leadingedge to radially restrain said flexible printing plate when saidactuator means is positioned in said clamping position, and secondfinger members interspersed with said first finger members along thelongitudinal extent of said plate-like body and having sloped surfaceportions engaging slots in said flexible printing plate flanged trailingedge to radially restrain said flexible printing plate when saidactuator means is positioned in said tensioning position.

5. The invention defined in claim 4 wherein said plate-like body isprovided with a groove in said body leading edge and with a groove insaid body trailing edge, said first finger member sloped surfaceportions being received in said body leading edge groove when said plateretention member is moved in a circumferential direction to saidclamping position.

1. A saddle for attaching to a printing cylinder a flexible printingplate having like flanged and slotted leading and trailing edges formedessentially at right angles to the plate principal surface andcomprising, in combination: a rigid plate-like body of generallysemi-circular crosssectional configuration defined in part by a pair oflongitudinal edges; attachment means adjacent the concave surface ofsaid plate-like body for mounting said body on a printing presscylinder; a pair of plate retention members respectively locatedadjacent said body pair of longitudinal edges and each having alternateextreme positions for clamping and for tensioning; mounting meanssecuring said plate retention members to said body and restrictingmovement of said plate retention members to circumferential directionsrelative to said body longitudinal edges and relative to said retentionmember clamping and tensioning positions; a pair of actuator meansrespectively connected to said pair of plate retention members and eachbeing mounted for actuation to alternately move a cooperating connectedplate retention member to said alternate extreme plate clamping andplate tensioning positions; first means in each said plate retentionmember for engaging and radially restraining a printing plate flangedand slotted leading edge and for urging said engaged plate flanged andslotted leading edge against one of said body longitudinal edges onmovement of said plate retention member by the connected one of saidactuator means to one of said extreme plate clamping positions; andsecond means in each said plate retention member for engaging andradially restraining a printing plate flanged and slotted trailing edgeand for urging said engaged plate flanged and slotted trailing edge awayfrom the other of said body longitudinal edges on movement of said plateretention member by the connected one of said actuator means to one ofsaid extreme plate tensioning positions.
 2. The saddle defined by claim1 wherein each said actuator means comprises an actuator bar elementhaving slots and movable in longitudinal directions with respect to saidplate-like body, and wherein said plate retention member connected tosaid actuator means bar element is provided with diagonal slot elementsand with cooperating roller cams each further cooperating with saidactuator bar element slots, said roller cam and diagonal slot elementsdirecting forces developed by said connected actuator means from linesalong said bar element longitudinal directions to lines along said plateretention means circumferential directions to move the connected one ofsaid retention members to said clamping position and to said tensioningposition when said actuator means is operated to move said mountingmeans to and from said plate tensioning position.
 3. The inventiondefined by claim 2 wherein said diagonal slot elements are provided ateach slot end with a reverse-angle pocket acting as a detent for thecooperating one of said roller cam elements, said reverse-angle pocketslocating the cooperating actuator means and mounting means in said plateclamping and plate tensioning positions.
 4. The invention defined byclaim 1 wherein said plate retention members each have spring-likefinger members oriented relative to said plate-like body in a generallyradial direction and extending substantially throughout the longitudinalextent of said plate-like body, said finger members further comprisingfirst finger members engaging the flexible printing plate flangedtrailing edge when tensioning said flexible printing plate and havingsloped surface portions engaging slots in said flexible printing plateflanged leading edge to radially restrain said flexible printing platewhen said actuator means is positioned in said clamping position, andsecond finger members interspersed with said first finger members alongthe longitudinal extent of said plate-like body and having slopedsurface portions engaging slots in said flexible printing plate flangedtrailing edge to radially restrain said flexible printing plate whensaid actuator means is positioned in said tensioning position.
 5. Theinvention defined in claim 4 wherein said plate-like body is providedwith a groove in said body leading edge and with a groove in said bodytrailing edge, said first finger member sloped surface portions beingreceived in said body leading edge groove when said plate retentionmember is moved in a circumferential direction to said clampingposition.